Accurately determining the position of a user or mobile device within an indoor setting presents various challenges. For example, global positioning systems (GPS) technologies do not work well within an enclosed building, where the mobile device's communications with the GPS satellites can be impeded by the surrounding structure. Further, available consumer devices are limited in their communication capabilities, sensing capabilities (e.g., mobile device microphones), the accuracy of their internal clocks, available power, etc. Accordingly, obtaining highly accurate, real-time location information on a mobile user within enclosed buildings (or where GPS positioning is otherwise unavailable) is difficult without nontrivial modifications to the hardware of available mobile devices.